refactor the code related to xtcp (#3449)

client/visitor/visitor.go

@@ -0,0 +1,77 @@
+// Copyright 2017 fatedier, fatedier@gmail.com
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package visitor
+
+import (
+	"context"
+	"net"
+	"sync"
+
+	"github.com/fatedier/frp/pkg/config"
+	"github.com/fatedier/frp/pkg/transport"
+	"github.com/fatedier/frp/pkg/util/xlog"
+)
+
+// Visitor is used for forward traffics from local port tot remote service.
+type Visitor interface {
+	Run() error
+	Close()
+}
+
+func NewVisitor(
+	ctx context.Context,
+	cfg config.VisitorConf,
+	clientCfg config.ClientCommonConf,
+	connectServer func() (net.Conn, error),
+	msgTransporter transport.MessageTransporter,
+) (visitor Visitor) {
+	xl := xlog.FromContextSafe(ctx).Spawn().AppendPrefix(cfg.GetBaseInfo().ProxyName)
+	baseVisitor := BaseVisitor{
+		clientCfg:      clientCfg,
+		connectServer:  connectServer,
+		msgTransporter: msgTransporter,
+		ctx:            xlog.NewContext(ctx, xl),
+	}
+	switch cfg := cfg.(type) {
+	case *config.STCPVisitorConf:
+		visitor = &STCPVisitor{
+			BaseVisitor: &baseVisitor,
+			cfg:         cfg,
+		}
+	case *config.XTCPVisitorConf:
+		visitor = &XTCPVisitor{
+			BaseVisitor:   &baseVisitor,
+			cfg:           cfg,
+			startTunnelCh: make(chan struct{}),
+		}
+	case *config.SUDPVisitorConf:
+		visitor = &SUDPVisitor{
+			BaseVisitor:  &baseVisitor,
+			cfg:          cfg,
+			checkCloseCh: make(chan struct{}),
+		}
+	}
+	return
+}
+
+type BaseVisitor struct {
+	clientCfg      config.ClientCommonConf
+	connectServer  func() (net.Conn, error)
+	msgTransporter transport.MessageTransporter
+	l              net.Listener
+
+	mu  sync.RWMutex
+	ctx context.Context
+}